Numerous applications require vacuum pumps to deliver (partial) vacuum for use in different industrial, scientific and medical processes. These different processes require different levels of vacuum leading to a range of different pump types and pumping principles. Two main parameters of a vacuum pump are the achievable flow and the achievable vacuum level, i.e. pressure level. Every pumping principle has its specific benefits and downsides, and every application has its specific requirements for the pump. Usually a pump being able to provide a higher level of vacuum or a higher flow is larger and more difficult to manufacture. Thus, a compromise between required flow, maximum vacuum level, manufacturing costs, construction size and other parameters has to be found when choosing or manufacturing a vacuum pump for a specific application.
One application area for vacuum pumps is the field of breast pump devices, i.e. devices for extracting milk from the breast of a lactating woman. Such devices usually include a vacuum pump for delivering a (partial) vacuum, which is applied to the breast of a woman in order to suck milk out of the breast. WO 2012/127405 A1 discloses a breast pump device operable to generate a negative pressure. The maximum negative pressure that can be applied by a breast pump device is a function of the maximum pressure value that the used (partial) vacuum pump can provide. If a higher level of vacuum is required, a different type of pump is required usually making the breast pump device larger and/or more expensive to manufacture.
In US 2005/0283112 A1 a breast pump is presented. The device includes a breast shield adapted to fit over a nipple of a breast and a flow line coupled to the breast shield. The flow line is adapted to allow air to flow there through a pump coupled to the breast shield via the flow line. The pump includes a pump intake and a pump exhaust and is operable to create a pressure drop between the nipple and the pump, wherein the pressure drop creates a suction at the breast shield by lowering the pressure of air in the flow line. A blow-back valve is disposed between the flow line and the pump and has a valve piston disposed in a valve housing The valve housing includes a flow line aperture that communicates via the flow line with the breast shield, a valve inlet adapted to communicate external to the flow line, and a valve exhaust adapted to communicate external to the flow line. The valve piston is adapted to alternatively seal the valve inlet and the valve exhaust.
In US 2013/0165852 A1 an electric breast milk pump is presented. The pump has an electric motor, a pump driven by the motor, a suction cup, an electrically activated first three-way valve in a suction line, an electrically activated second three-way valve in a pressure line, an electronic control system, which sets the electric motor into an operating mode or an idle mode depending on an activation of a switch. In the operating mode, it operates the electric motor and the electrically activated first and second three-way valves in cycles, which comprise a suction phase, in which the electric motor is switched on, the inlet of the pump is connected to the suction cup via the first three-way valve and a floater valve, the pump outlet is connected via the second three-way valve.